The field of ferroelectricity has greatly expanded and changed recently. In addition to classical organic and inorganic ferroelectrics as well as composite ferroelectrics new fields and materials ...
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The field of ferroelectricity has greatly expanded and changed recently. In addition to classical organic and inorganic ferroelectrics as well as composite ferroelectrics new fields and materials have appeared, important for both basic science and application and showing technological promise for novel multifunctional devices. Most of these fields were unknown or inactive 20 to 40 years ago. Such new fields are multiferroic magnetoelectric systems, where the spontaneous polarization and the spontaneous magnetization are allowed to coexist, incommensurate ferroelectrics, where the periodicity of the order parameter is incommensurate to the periodicity of the underlying basic crystal lattice, ferroelectric liquid crystals, dipolar glasses, relaxor ferroelectrics, ferroelectric thin films and nanoferroelectrics. These new fields are in addition to basic physical interest also of great technological importance and allow for new memory devices, spintronic applications and electro‐optic devices. They are also important for applications in acoustics, robotics, telecommunications and medicine. New developments in relaxors allow for giant electromechanical and electrocaloric effects. The book is primarily intended for material scientists working in research or industry. It is also intended for graduate and doctoral students and can be used as a textbook in graduate courses. Finally, it should be useful for everybody following the development of modern solid‐state physics.Less

Advanced Ferroelectricity

Robert Blinc

Published in print: 2011-08-25

The field of ferroelectricity has greatly expanded and changed recently. In addition to classical organic and inorganic ferroelectrics as well as composite ferroelectrics new fields and materials have appeared, important for both basic science and application and showing technological promise for novel multifunctional devices. Most of these fields were unknown or inactive 20 to 40 years ago. Such new fields are multiferroic magnetoelectric systems, where the spontaneous polarization and the spontaneous magnetization are allowed to coexist, incommensurate ferroelectrics, where the periodicity of the order parameter is incommensurate to the periodicity of the underlying basic crystal lattice, ferroelectric liquid crystals, dipolar glasses, relaxor ferroelectrics, ferroelectric thin films and nanoferroelectrics. These new fields are in addition to basic physical interest also of great technological importance and allow for new memory devices, spintronic applications and electro‐optic devices. They are also important for applications in acoustics, robotics, telecommunications and medicine. New developments in relaxors allow for giant electromechanical and electrocaloric effects. The book is primarily intended for material scientists working in research or industry. It is also intended for graduate and doctoral students and can be used as a textbook in graduate courses. Finally, it should be useful for everybody following the development of modern solid‐state physics.

The conditions leading to the simultaneous existence of ferroelectric, ferromagnetic or anti‐ferromagnetic properties are discussed. Special attention is paid to the problem of why there are so few ...
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The conditions leading to the simultaneous existence of ferroelectric, ferromagnetic or anti‐ferromagnetic properties are discussed. Special attention is paid to the problem of why there are so few magnetoelectrics. The different mechanisms leading to ferroelectric multiferroics are presented. The linear and quadratic magnetoelectric effect are discussed as well as the modification of the Vogel–Fulcher relation in external fields. The case where there are both polar nanoregions and magnetic nanoregions is discussed and the theory of such bi‐relaxors is presented.Less

Magnetoelectric ferroelectrics

Robert Blinc

Published in print: 2011-08-25

The conditions leading to the simultaneous existence of ferroelectric, ferromagnetic or anti‐ferromagnetic properties are discussed. Special attention is paid to the problem of why there are so few magnetoelectrics. The different mechanisms leading to ferroelectric multiferroics are presented. The linear and quadratic magnetoelectric effect are discussed as well as the modification of the Vogel–Fulcher relation in external fields. The case where there are both polar nanoregions and magnetic nanoregions is discussed and the theory of such bi‐relaxors is presented.

Relaxors are site‐ and charge‐disordered crystals or solid solutions where charge disorder induces random fields. They are characterized by the appearance of polar nanoclusters that are much smaller ...
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Relaxors are site‐ and charge‐disordered crystals or solid solutions where charge disorder induces random fields. They are characterized by the appearance of polar nanoclusters that are much smaller than typical ferroelectric domains, and a broad distribution of relaxation times. The various physical properties of relaxors are discussed and the spherical random‐bond–random‐field model of these systems is also presented. As the various polar units in nanoclusters vary in orientation and size the system cannot be described by an ordering field of fixed length as in Ising systems. The order parameter field is thus continuous. The phase diagrams, neutron scattering, Raman spectra, heat conductivity and specific heat as well as the NMR lineshapes and relaxation times are discussed. The existence of electric‐field‐induced critical end points in the phase diagrams is demonstrated and discussed within the Landau theory.Less

Relaxor ferroelectrics

Robert Blinc

Published in print: 2011-08-25

Relaxors are site‐ and charge‐disordered crystals or solid solutions where charge disorder induces random fields. They are characterized by the appearance of polar nanoclusters that are much smaller than typical ferroelectric domains, and a broad distribution of relaxation times. The various physical properties of relaxors are discussed and the spherical random‐bond–random‐field model of these systems is also presented. As the various polar units in nanoclusters vary in orientation and size the system cannot be described by an ordering field of fixed length as in Ising systems. The order parameter field is thus continuous. The phase diagrams, neutron scattering, Raman spectra, heat conductivity and specific heat as well as the NMR lineshapes and relaxation times are discussed. The existence of electric‐field‐induced critical end points in the phase diagrams is demonstrated and discussed within the Landau theory.

A theory of the electrocaloric effect is presented. It is shown that the electrocaloric effect in ferroelectrics is maximal at the electric‐field‐induced first‐order phase transition, whereas it is ...
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A theory of the electrocaloric effect is presented. It is shown that the electrocaloric effect in ferroelectrics is maximal at the electric‐field‐induced first‐order phase transition, whereas it is maximal in relaxors at the electric‐field‐induced critical end point. The maximum efficiencies ΔT/ΔE and ΔS/ΔE for various samples are presented. It is shown that in relaxors a giant electrocaloric effect takes place at the critical end point where also the electromechanical response is largest. A universal expression for the maximum temperature change in the saturation regime is derived that is valid both for electrocaloric and magnetocaloric systems.Less

Electrocaloric effect in ferroelectrics and ferroelectric thin films

Robert Blinc

Published in print: 2011-08-25

A theory of the electrocaloric effect is presented. It is shown that the electrocaloric effect in ferroelectrics is maximal at the electric‐field‐induced first‐order phase transition, whereas it is maximal in relaxors at the electric‐field‐induced critical end point. The maximum efficiencies ΔT/ΔE and ΔS/ΔE for various samples are presented. It is shown that in relaxors a giant electrocaloric effect takes place at the critical end point where also the electromechanical response is largest. A universal expression for the maximum temperature change in the saturation regime is derived that is valid both for electrocaloric and magnetocaloric systems.

Magnetoelectric materials are those where the magnetism can be affected by an external electric field, or, conversely, those where electric polarization is affected by a magnetic field. Many ...
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Magnetoelectric materials are those where the magnetism can be affected by an external electric field, or, conversely, those where electric polarization is affected by a magnetic field. Many magnetoelectric materials are multiferroic, meaning that they simultaneously possess spontaneous ferroelectric and magnetic ordering, but this is not an essential requirement. Magnetoelectrics and multiferroics have become an important area of research on account of their interesting fundamental science and potentially useful applications in memory devices and magnetovoltaic transducers. This chapter reviews the types of magnetoelectric coupling that exist, the magnitude of the effect and its limits, the types of materials that have it, and how is it measured. Throughout, the chapter emphasizes points that are usually overlooked in the literature, such as non-oxide materials, fundamental differences between linear and quadratic coupling, or experimental artifacts in measurements.Less

Magnetoelectric coupling and multiferroic materials

Gustau CatalanJames F. Scott

Published in print: 2012-08-30

Magnetoelectric materials are those where the magnetism can be affected by an external electric field, or, conversely, those where electric polarization is affected by a magnetic field. Many magnetoelectric materials are multiferroic, meaning that they simultaneously possess spontaneous ferroelectric and magnetic ordering, but this is not an essential requirement. Magnetoelectrics and multiferroics have become an important area of research on account of their interesting fundamental science and potentially useful applications in memory devices and magnetovoltaic transducers. This chapter reviews the types of magnetoelectric coupling that exist, the magnitude of the effect and its limits, the types of materials that have it, and how is it measured. Throughout, the chapter emphasizes points that are usually overlooked in the literature, such as non-oxide materials, fundamental differences between linear and quadratic coupling, or experimental artifacts in measurements.